[Drake] Need PTT Relay for TX4C

[Garey Barrell]

Charlie -

The "correct" replacement relay is the P&B (Tyco) R10-E1-Y4-V2.5k, same 
relay used in the "late" T-4XC and TR-4C, which IS available from Mouser 
and Digikey among others.   About $15.

If your old relay is a Varley with a 15k coil, you need to add a 1.5k 1W 
resistor in series with the coil, otherwise a drop-in replacement.  Look 
at the socket for V10, the 6FQ7 (or 6EV7).  If there is a 1.5k, 1W 
resistor connected between Pin 6 and Pin 9, just plug in the new relay.  
If there is NO resistor, remove the wire connected to Pin 6 and move it 
to Pin 9, add a 1.5k, 1W resistor between Pin 6 and Pin 9, and plug in 
the new relay.

The 15k ohm coil relays were failure prone, primarily because of the 
very fine wire needed.  The bobbin would swell,  especially in humid 
conditions, stressing and breaking the wire.  This is why T-4XC's that 
have been stored in the garage for a while often have a bad relay!  The 
2.5k ohm coil of course uses considerably larger wire.
-- 
73, Garey - K4OAH
Glen Allen, BA

Drake 2-B, 4-B & C-Line Service Supplement CDs
<www.k4oah.com>

73, Garey - K4OAH
Glen Allen, VA

Drake 2-B, 4-B & C-Line Service Supplement CDs
<www.k4oah.com>



k5mbx at hug-a-bug.com wrote:
> Hi all,
> I need a PTT Relay for the Drake TX4C. Does anyone know where I can get
> one? This the PTT, Muting, Bias Control Relay in the TX4C.
> It is the plug in type with a 14 pin sockett. The one in this TX4C
> was made in England. It is a Clare/Varly brand with a 15K resistance coil.
> It also has VP4 and CAB-120 printed on it.  Thanks, Charlie Hugg, K5MBX
>
>
>